KMCE's Workbench

[David Holman]

Me three, also in 7mm. The aim is to do it in plastic sheet/strip, with whitemetal fittings. Only need one or two, so not thinking resin casting with it.

[DSERetc]

Posted November 25 2018

A little teaser for the next loco on the bench

Hello Ken,

I have just come across your posts and I have another possible answer to your teaser.

Sometime in the early 1950s, I was travelling from Dublin to Bray.    Somewhere along the way I looked out the window of the carriage to see what engine was pulling us.   I saw the side tanks, cab and bunker and it seemed to be one of the 0-6-2T 670 class tank engines.    When we reached Bray,  imagine my surprise and joy when I saw a tank engine with outside cylinders.    It was 850  the  2-6-2T  tank engine.    It was the only engine with outside cylinders I ever saw in Bray.     It was built in 1928 and was said to have parts of the unbuilt Woolwich  2-6-0.   The side tanks, cab and bunker, even the hand rails, seem to be almost identical to those on the 670s.  So if you have these stored on your computer, and if you can get a Woolwich frame and motion,  a pony truck and a boiler,   you could have another model of an engine running on the  DSER.

Great Work.

DSERetc

 

[KMCE]

Some minor tweaks to the 3D model to Rev 4 to include changes to the lower straps on the uprights to more prototypical detail.  Also the holes for the bars were opened up to ease the installation of same.

 

And the advantage of printers is the ability to gerenate a train quickly.

 

I'm planning to use brass compensated chassis for these, so there is still some work to do, but not having to do all the uprights and rivet detail on the bodies is quite a relief.  Will need to add weight to the wagons bring them up to the weight of the other wagons already made.

Very pleased with the results & quality of the print.

 

 

[popeye]

Could the underframe not be printed too?

And, is there a need for a compensated chassis as most 4 wheel wagon models

don't have them?

[KMCE]

23 minutes ago, popeye said:

Could the underframe not be printed too?

Thanks for the comment.

 

For OO gauge, it would be possible, however to provide enough strength the thickness of resin would make printing for 21mm difficult, but not impossible.  The overall wagon width at the axle location is c. 30 - 31mm whilst the pinpoint axle dimension is 28mm, so it would be rather close.  I am a fan of the detail in the brass underframes with cast axleboxes and springs, so made sense for me.

Most of my wagons are compensated as I am working to P4 standards, with the exception being the very short DW&WR ballast wagons which have a 6' wheel base.

I would consider an underframe print for an OO version if there was an interest.

[popeye]

Would you consider printing the wagon bodies?

Or other wagons like open plank wagons.

[David Holman]

The wagons look great, Ken. How long does each one take to print? Not sure it would be practical to resin cast sides and ends for open structures like these, so certainly the way to go. However, just for comparison, a set of resin castings for a van take about 30-40 minutes to set, with about another half hour to assemble into a box, so am wondering if I need to consider changing to 3D printing any time soon?

[Mayner]

We have successfully printed wagons chassis suitable for OO & 21mm gauge, though a rigid brass or compensated chassis with metal detail castings is likely to be a better option using S4 or EMF wheel standards. A brass chassis is likely to be freer running and more dimensionally stable than a 3D printed chassis.

The main risk in printing a chassis is part breakage as many of the SLA resins are very brittle, particularly in cold weather.

We originally considered resin casting for production version of the CIE Brake Van but settled on 3D printing as we were unable to find a business with vacuum resin casting capability as small scale manufacture has moved on to 3D printing.

We overcome the brittleness problem for wagon chassis by using a resin with ABS properties and have printed the IRCH wagon chassis in one piece complete with brake gear, door springs and hopper operating gear something that would be extremely difficult to achieve using resin casting or plastic injection molding.

I use a freelance designer with experience in 3D printing, local and Chinese 3D printing bureau as it would have taken a long time to develop adequate 3D modelling skills to design and print a 3D wagon and could not justify the expense (at this stage) of buying a SLA printer capable of volume production.

The challenge from my perspective was finding a designer and a printing house prepared to push the boundaries on what could be achieved using 3D printing.

[KMCE]

16 hours ago, popeye said:

Would you consider printing the wagon bodies

Pop,

Up to now, I had not considered printing as a venture, but if people are interested in the body only, they would be immediately available for order.  I would need to think of a price - something reasonable naturally.  The cost is not in the physical printing, but in the origainal design and development.

 

7 hours ago, David Holman said:

How long does each one take to print?

David,

If one were to print a single unit at a time it takes 3 hours, but my build plate can take up to 5 wagons at a time - the time is not per unit but the build height, irrespective of the amount of material on the plate (resin SLA printing).  Thus I can print 5 bodies in three hours.

As mentioned above, the time is not in the printing, and as John attested above, the time is in the design of the model and running of test prints to establish a final design.  What looks good in 3D CAD, even if it is to exact scale, does not always translate to a reasonable looking model.  Some tweaks are needed to provide a reasonable looking model whilst maintaining strength.

 

6 hours ago, Mayner said:

a rigid brass or compensated chassis with metal detail castings is likely to be a better option

John,

Agreed.  It did not even occur to me to print a chassis for this model for P4.  

I am very interested in your comments regarding the ABS type of resin; so far I have used three types of resin, a translucent green as seen on other posts which provides very detailed models, but is very brittle.  The standard resin (Anycubic grey) proved to be less brittle but detail was not as good.  The problem with both those resins was the need to use IPA (Isopropyl Alcohol, not India Pale Ale) to clean up, which really is a pain to use and then clean afterwards.  The models above were printed with the Elgoo Mars water washable resin, which I have found to have good physical properties whilst holding detail - the ability to clean up with water makes the process much eaiser.

The detail on your chassis is excellent - I assume these are gauged for OO?

I may look at developing a simple OO chassis for these (and others) which will be suitable for the short wheel base of earlier Irish wagons.

 

[KMCE]

Given the success of the cattle wagon, I had drawings from HMRS for the DWWR Convertible wagon, which was quite easy to translate to CAD (particuarly for a model build).  With the experience and methodology used for the cattle wagon, it was possible to develop a basic model in 3D for one of these wagons.

 

Again run through the printer we get:

 

There is a some tidying up needed on these models.  The model is supported on the build plate by an network of thin supports (see below) - this is to ensure that each layer, particulary new layers are lifted of the base film without distorting.  These supports leave very small marks that need cleaning up before the model can progress.

 

Anyway, on to building chassis for these wagons.  Should keep me busy for a while!!

[David Holman]

Fascinating! Many thanks Ken and others. The quality of 3D printing has certainly improved massively in the last couple of years. Will look forward to seeing how these wagons progress.

[WRENNEIRE]

I'll take a half dozen Ken, weathered!

[popeye]

Modern technology, every year there are improvements in quality.

Imagine what it will be like in 5 years. 

[KMCE]

Little bit of progress.  Wagon lightly sandblasted prior to a dusting of paint to get a feel for how the detail will work.  Coming up rather nicely.

[Mayner]

5 minutes ago, KMCE said:

Little bit of progress.  Wagon lightly sandblasted prior to a dusting of paint to get a feel for how the detail will work.  Coming up rather nicely.

The shortie (13-14')

 

7 hours ago, KMCE said:

Given the success of the cattle wagon, I had drawings from HMRS for the DWWR Convertible wagon, which was quite easy to translate to CAD (particuarly for a model build).  With the experience and methodology used for the cattle wagon, it was possible to develop a basic model in 3D for one of these wagons.

 

Again run through the printer we get:

 

There is a some tidying up needed on these models.  The model is supported on the build plate by an network of thin supports (see below) - this is to ensure that each layer, particulary new layers are lifted of the base film without distorting.  These supports leave very small marks that need cleaning up before the model can progress.

 

Anyway, on to building chassis for these wagons.  Should keep me busy for a while!!

Cleaning up removing un-cured resin and the supporting structure is very labour intensive and a significant cost in SLA printing. 

The business that I use for prototyping was very reluctant to take on volume production due to the risk of a slender part being knocked over during the "build" and loosing a nights production.

Both my suppliers use isopropyl for clean up, one uses a converted car painters mixing room with mechanical ventilation and intrinsically safe electrics for the clean up process.

Some models are printed vertically or at an angle to improve strength and improve finish by reducing the layering effect and the cleaning up to one face.

The wagon chassis were designed for 21mm gauge wheelsets, the brakevan steps were printed integral with the chassis to reinforce the w iron axlebox spring assembly, while we increased the thickness of the W irons on the IRCH wagon chassis. 

We learned a lot about the capabilities and limitations of the 3D printing process during the design of the Brake Van originally designed as a pattern for resin casting with a lot of individual parts, it went through several iterations before we arrived at the final design once it was established that resin casting was not a practical proposition, by contrast apart from missing some of the rivet detail we got it right first time with the IRCH open wagon.

[jhb171achill]

I would certainly take a couple of those if they were a reasonable price!

[KMCE]

Some progress on the convertible wagon.  Very pleased with how these are turning out - some light sand blasting followed by a coat of paint should  help.

[murrayec]

Amazing Ken,

I cant wait to do my O ones, but will have to as not enough time- I got the printer in March and still haven't used it!!

Eoin

 

[David Holman]

Well done Ken, always great to see folk pushing the boundaries. Does the green track base also involve alchemy?

[KMCE]

Busy yard in the evening sunshine......

 

[KMCE]

On 15/6/2021 at 10:16 PM, David Holman said:

Does the green track base also involve alchemy

Yes, this was noted in the 21mm survey on RTR track.  I have managed to develop a print for 21mm which with a limited amount of work will provide 21mm track without the need for all the soldering & associated track gauges.

Need to develop up the points a little further berfore they are a simple solution for 21mm development.

[David Holman]

10 minutes ago, KMCE said:

Busy yard in the evening sunshine......

 

That's your own house in the background then...

[KMCE]

1 minute ago, David Holman said:

That's your own house in the background then...

But of course - Victorian naturally!!

 

This is the old Militia Barracks located adjacent to the reminants of Murrough Station in Wicklow.  This backdrop was developed from a series of photos I took a few weeks back of what's left of the old Murrough station house, station wall & Militia Barracks, now called Marine house (currently a non-denominational primary school).  The houses just visible over the wall are new builds, but by just keeping the roofs, I can maintain a timeless backdrop.

Another shelftop layout being developed to take trial the printed track etc.

[David Holman]

Works really well, Ken.

[KMCE]

As a follow on from some earlier queries on printing a chassis for these wagons, I had a go at designing something that would work, both to capture the prototypical look and also working within the limits of resin printing.  I wanted to achieve a realistic looks, however it does require some thickness to make sure there is strength both to hold the axles & tolerate handling etc.

The chassis build allows for 28mm axles, so both 21mm & OO gauge is possible.  I also integrated the chassis into the wagon bodies & re-printed following many trial prints to establish what would work for the chassis.

Now we have the Mk V cattle wagon:

Cast buffers and 0.5mm rod for the bars.  Need to add a roof (either brass or plastic) and work out whether I want cattle inside or not.

 

Convertible wagon can also benefit from this chassis design, so we now have the Mk II version

Amazing what can be seen from close up photos -  there is a lot of small particles & dust needs to be cleaned away from the modes prior to painting, along with some sanding / filing on the angled elements such as the brake lever.

 

Rather pleased as to how these have turned out - they also appear to be good runners which is also good; there is some play in the axlebox for the axle to move which allows some compensation.  They will need weight added however as they weigh in under 20g each; for comparison the brass built wagons are 50 - 60g.

Better get the lead out!!!

Ken

[Galteemore]

Those are top notch Ken. Instantly recognisable Irish prototypes and nicely finished. Will look wonderful when painted up.

[jhb171achill]

T O P class, as always and as expected! You're building up a serious collection of older wagons.

I'd love to be able to get prototypes of that sort of vintage to run on my layout, as more than a few of them were still kicking about in places like Tramore, West Cork, and Kerry branch lines until this side of 1960.

[murphaph]

Are they pinpoint axles running in brass bearings Ken or directly in the resin? Fantastic work.

[Georgeconna]

Pay tell how did you do the Corrugated roof? Is that Printed too?

[David Holman]

Tasty. Well done Ken.

[KMCE]

Many thanks for the comments guys - much appreciated.

 

13 hours ago, murphaph said:

Are they pinpoint axles running in brass bearings Ken or directly in the resin?

Murph,  they are pinpont axles running in the resin.  So far they run freely, how well they will wear is hard to say - given the amount of running I do, they will last!  I would anticipate that with a small amount of clock oil in the bearing cone in the resin, would provide sufficient lubrication to reduce wear.

 

11 hours ago, Georgeconna said:

Corrugated roof?

George,  Corugated roof is cut from a sheet I bought some time ago - I will need to go back through my orders to try to find where I bought it as  I will need more for a run of Ashbury vans I'm planning.  What is nice, is it is a single sheet c. A5, without any seams so can be cut to various sizes.   If I find where I bought it, I'll post up the details.

 

Ken

[Galteemore]

IIRC Ambis Engineering do or did corrugated sheet like that. http://www.ambisengineering.co.uk/Products/Products_Index.htm

[jhb171achill]

30 minutes ago, Galteemore said:

IIRC Ambis Engineering do or did corrugated sheet like that. http://www.ambisengineering.co.uk/Products/Products_Index.htm

Don't see it advertised - I have emailed them. I need some curved corrugated iron sheet 00 scale for convertible wagons roofs.

[Galteemore]

They operate at the other end of the supplier spectrum to Hornby etc and production fluctuates! I am pretty sure I saw it at Scaleforum a few years ago. SE Finecast do a thin corrugated sheet which I think would be more amenable to bending than Evergreen sheet and certainly than Ratio’s toffee-like slabs.

 

[David Holman]

Slater's Plasticard do 7mm scale corrugated sheets, so worth checking their website to see if 4mm available.